FR2574367A1 - Marine structure with vertical taut anchoring. - Google Patents
Marine structure with vertical taut anchoring. Download PDFInfo
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- FR2574367A1 FR2574367A1 FR8418863A FR8418863A FR2574367A1 FR 2574367 A1 FR2574367 A1 FR 2574367A1 FR 8418863 A FR8418863 A FR 8418863A FR 8418863 A FR8418863 A FR 8418863A FR 2574367 A1 FR2574367 A1 FR 2574367A1
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- Prior art keywords
- float
- central
- platform
- peripheral
- container
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
- B63B35/44—Floating buildings, stores, drilling platforms, or workshops, e.g. carrying water-oil separating devices
- B63B35/4413—Floating drilling platforms, e.g. carrying water-oil separating devices
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
- B63B1/02—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement
- B63B1/04—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with single hull
- B63B1/048—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with single hull with hull extending principally vertically
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B21/00—Tying-up; Shifting, towing, or pushing equipment; Anchoring
- B63B21/50—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers
- B63B21/502—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers by means of tension legs
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
- B63B1/02—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement
- B63B1/04—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with single hull
- B63B2001/044—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with single hull with a small waterline area compared to total displacement, e.g. of semi-submersible type
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- Ocean & Marine Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Earth Drilling (AREA)
Abstract
Description
La presente invention concerne une plate-forme petroliere offshore a cables tendus. Ce type de plateforme est ancre au fond de la mer par des lignes d'ancrage verticales ou tendons qui sont deployes entre la plate-forme flottante et un systeme d'ancrage fixe sur le fond de la mer. Ces tendons sont tendus par une force dite de "pre-tension" tres Importante qui s'oppose aux excursions verticales et horizontales de la plate-forme. Cette pre-tension est obtenue par un exces de flottabilite ,en amarrant la plate-forme aux tendons avec un tirant d'eau superleur a celui de sa flottaison libre.Ce type de plate-forme ne peut s'orienter librement et son pilonnement est pratiqu ment bloque afin d'avoir une periode propre de pilonnement inferieure a 3 secondes ,de facon a ne pas etre excitee significativement par la houle . En consequence ce type de plate-forme installe dans une region polaire, ne peut se degager des glaces par un mouvement de pilonnement contrôle
En plus de la pre-tension statique, les tendons subissent des tensions dynamiques perlodiques. La tension totale par tendon est donc la somme ou la difference de la pre-tension et de la valeur extrême de la variation dynamique de la tension.Il est donc necessaire dFeviter d'une part la sur-tension et d'autre part le relachement des tendons. Pour des plate-formes de grand deplacement les tensions dynamiques deviennent considerables et la pre-tension necessaire devient rapidement economiquement prohibitive ,si l'etat de mer centenaire de design est celui d'une mer forte ,comme par exemple la Mer du Nord, ou la hauteur de la vague maximale est d'environ 30 metres, pour une periode de 18 secondes. The present invention relates to an offshore oil platform with stretched cables. This type of platform is anchored to the bottom of the sea by vertical anchor lines or tendons which are deployed between the floating platform and a fixed anchor system on the sea bottom. These tendons are stretched by a force very important "pre-tension" which opposes the vertical and horizontal excursions of the platform. This pre-tension is obtained by an excess of buoyancy, by mooring the platform to the tendons with a draft greater than that of its free flotation. This type of platform cannot be oriented freely and its heaving is practically blocked in order to have a clean heaving period of less than 3 seconds, so as not to be significantly excited by swell. Consequently this type of platform installed in a polar region, cannot be released from the ice by a controlled heaving movement
In addition to the static pre-tension, the tendons undergo dynamic perlodic tensions. The total tension per tendon is therefore the sum or difference of the pre-tension and the extreme value of the dynamic variation of the tension. It is therefore necessary to avoid on the one hand the over-tension and on the other hand the relaxation tendons. For large displacement platforms, the dynamic tensions become considerable and the necessary pre-tension quickly becomes economically prohibitive, if the design century-old sea state is that of a strong sea, such as the North Sea, or the maximum wave height is around 30 meters, for a period of 18 seconds.
La plate-forme selon l'invention permet de remedier a ces inconveniants. The platform according to the invention makes it possible to remedy these drawbacks.
Elle comporte en effet d'une facon generaît, une partie peripherique flottante qui coulisse verticalement autour d'une partie centrale flottante amarree par des tendons verticaux pre-tendus. Les deux parties comprennent chacune un pont horizontal supporte rigidement sur un flotteur etanche entierement immerge ,au moyen d'une structuresupport semi-immergee. La partie peripherique est d'un d placement plus important que la partie centrale pour mi ni mi mer les variations dynamiques des tensions dans les tendons. C'est pourquoi la partie centrale supporte un minimum d'equipement lourd pour maximiser son rapport pre-tension/deplacement.In fact, it generally includes a floating peripheral part which slides vertically around a floating central part moored by pre-tensioned vertical tendons. The two parts each comprise a horizontal bridge rigidly supported on a completely submerged waterproof float, by means of a semi-submerged support structure. The peripheral part is of a more important displacement than the central part for mid or mid sea the dynamic variations of the tensions in the tendons. This is why the central part supports a minimum of heavy equipment to maximize its pre-tension / displacement ratio.
Selon une forme d'utilisation preferentielle, le flotteur peripherique est utilise pour stocker des fluides dont la densite est inférieure a l'eau de mer. According to a preferred form of use, the peripheral float is used to store fluids whose density is lower than sea water.
Le volume du flotteur peripherique est optimise pour d'une part maximiser sa masse ajoutee en pilonnement et d'autre part pour prot@ger efficacement la partie centrale contre les forces de houle qui induisent des variations dynamiques importants dans les tendons. The volume of the peripheral float is optimized to on the one hand maximize its mass added in heaving and on the other hand to effectively protect the central part against swell forces which induce significant dynamic variations in the tendons.
La sasse ajoutee en pilonnement
permet a la partie peripherique d'avoir une periode propre superieure a 30 secondes pour ne pas etre excitez a la resonance par la houle oceanique ,tout en maintenant une surface de flottaison importante La partie peripherique isole la plate-forme centrale de l'action directe de la houle, car les pressions hydrodynamiques de la houle ne parviennent aux parois du flotteur central que par passage sous la base horizontale de la partie peripherique
En dotant la partie peripherique d'un tirant d'eau important, on reduit les variations dynamiques des tensions dans les tendons.Par exemple pour une houle extreme de periode 18 secondes ,en grande profondeur d'ancrage, une reduction d'environ 75 de la pression de la houle est obtenue par un flotteur peripherique possedant un tirant d'eau de 110 metres. De plus un tirant d'eau important redui-vkussi les forces de la houle sur la base de la plate-forme peripherique.The heap added in heaving
allows the peripheral part to have a clean period greater than 30 seconds so as not to be excited to resonance by ocean swell, while maintaining a large buoyancy surface The peripheral part isolates the central platform from direct action of the swell, because the hydrodynamic pressures of the swell reach the walls of the central float only by passing under the horizontal base of the peripheral part
By providing the peripheral part with a large draft, we reduce the dynamic variations of the tensions in the tendons. For example for an extreme swell of period 18 seconds, in great anchoring depth, a reduction of about 75 of the wave pressure is obtained by a peripheral float having a draft of 110 meters. In addition, a large draft reduces the wave forces on the base of the peripheral platform.
Afin d' obtenir une masse d'eau ajoutee importante relativement a son deplacement, le flotteur peripherique forme un recipient a paroi epaisse, ferme par un couvercle, mais sans fond, pour permettre le passage des tendons verticaux ,et pour que ceux-ci ne rentrent pas en contact avec la base des parois du flotteur peripherique quand l'excursion horizontale de la plate-forme est maximale. In order to obtain a large added mass of water relative to its displacement, the peripheral float forms a thick-walled container, closed by a cover, but without bottom, to allow the passage of the vertical tendons, and so that these do not do not come into contact with the base of the walls of the peripheral float when the horizontal excursion of the platform is maximum.
Le flotteur central est immerge a l'interieur dudit recipient dans lequel la structure-support de la partie centrale penetre ,par au moins un orifice d'axe vertical du couvercle (ou toit) epais du recipient. The central float is immersed inside said container into which the support structure of the central part penetrates, through at least one orifice with a vertical axis of the thick cover (or roof) of the container.
Selon une forme de realisation preferentielle, la structure-support de la partie centrale est entierement situee a l'interieur d'au moins un puit vertical amenage a l'interieur de la structure-support de la partie peripherique, lesdit puit debouchant directement dans le recipient au travers de l'orifice du toit qui lui correspond
Selon une forme de realisation preferentielle, la structure-support de la partie peripherique est un anneau cylindrique fixe de facon etanche sur son flotteur peripherique, et dont le puit interne contient la structure-support de la partie centrale, cette derniere etant aussi un anneau cylindrique qui coulisse dans-ledit puit interne et au travers de l'unique orifice du toit du recipient. According to a preferred embodiment, the support structure of the central part is entirely located inside at least one vertical well fitted inside the support structure of the peripheral part, the said well opening directly into the container through the corresponding roof opening
According to a preferred embodiment, the support structure of the peripheral part is a cylindrical ring fixed in a sealed manner on its peripheral float, and the internal well of which contains the support structure of the central part, the latter also being a cylindrical ring which slides in said internal well and through the single orifice of the roof of the container.
Selon une forme de realisation, le recipient a la forme d'un cylindre creux d'axe vertical. Cette forme se prete a une realisation en beton de sa paroi laterale. Selon une variante-,ladite paroi est realisee par des surfaces cylindriques. Selon une autre variation ladite paroi est realisee par des cylindres creux dont les axes verticaux sont tangents a un meme cercle horizontalgavec le toit du cylindre pouvant etre horizontal ou bien en forme de cone ou de dome tronque. According to one embodiment, the container has the shape of a hollow cylinder with a vertical axis. This form lends itself to concrete construction of its side wall. According to a variant, said wall is produced by cylindrical surfaces. According to another variation, said wall is produced by hollow cylinders whose vertical axes are tangent to the same horizontal circle with the roof of the cylinder possibly being horizontal or else in the form of a cone or truncated dome.
Selon une realisation preferentielle la forme du recipient s'apparente a un grand segment sphériques defini par des parois internes et externes telles que les lignes d'actions des pressions hydrodynailques qui s'exercent perpendiculairement aux parois, passent pour la tres grande favorite d'entre elles au travers d'une petite zone geometrique spheroidale incluse dans la cavite du recipient. According to a preferred embodiment the shape of the container is similar to a large spherical segment defined by internal and external walls such that the lines of action of the hydrodynail pressures which are exerted perpendicular to the walls, pass for the very great favorite of them through a small spheroidal geometric area included in the cavity of the container.
Selon une realisation preferentielle la plus grande dimension de ladite zone est approximativement egale a ltepaisseur moyenne du recipient, et le volume du recipient est approximativement egal a celui du volume de la cavite qu'il contient. Les formes de flotteurs peripheriques ainsi definies ,reduisent les moments de roulis et de tangage de la partie peripherique ,ce qui permet de reduire d'autant les variations dynamiques des tensions dans les tendons ,car ces derniers bloquent toute rotation relative entre les deux
parties de la plate-forme.According to a preferred embodiment, the largest dimension of said zone is approximately equal to the average thickness of the container, and the volume of the container is approximately equal to that of the volume of the cavity that it contains. The shapes of peripheral floats thus defined reduce the moments of roll and pitch of the peripheral part, which makes it possible to reduce all the more dynamic variations in tensions in the tendons, since the latter block any relative rotation between the two.
parts of the platform.
La zone spheroidale ainsi definie concentre les forces hydrodynamiques sous le centre de gravite de la plate-forme et leur resultante produit un couple de rotation qui s'oppose a celui de la resultante des forces hydrodynamiques qui s'exercent sur la structure-support de la partie peripherique. The spheroidal zone thus defined concentrates the hydrodynamic forces under the center of gravity of the platform and their resultant produces a torque which is opposed to that of the resultant of the hydrodynamic forces which are exerted on the support structure of the peripheral part.
La forme de segment spherique du flotteur peripherique possede d'autre part un faible coefficient de trainee qui en diminuant l'excursion moyenne de la plate-forme, reduit les tensions dynamiques dans les tendons. The spherical segment shape of the peripheral float also has a low drag coefficient which, by reducing the average excursion of the platform, reduces the dynamic tensions in the tendons.
Selon une variante de l'invention ,les moments hydrodynamiques de roulisStangage ne sont que partiellement transmis aux tendons, quand le coulissement de la partie peripherique est effectue par un moyen qui autorise une petite rotation relative entre les deux parties de la plate-forme. According to a variant of the invention, the hydrodynamic moments of rollStangage are only partially transmitted to the tendons, when the sliding of the peripheral part is carried out by a means which allows a small relative rotation between the two parts of the platform.
Un moyen de coulissement selon l'invention est une protuberance annulaire (ou bague) , en for de segment spherique fixez sur la paroi d'une structure-support centrale cylindrique qui coulisse dans un manchon circulaire fixe sur la paroi circulaire du puit intérieur d'une structure-support peripherique annulaire. Le centre geometrique dudit segment spherique etant sur l'axe vertical de symétrie commun aux deux structures-support La surface de ladite protuberance est recouverte par un metal inoxydable et auto-lubrifiant,, et la paroi du manchon au contact de la bague est recouverte d'une couche d'acier inoxydable. A sliding means according to the invention is an annular protuberance (or ring), in the shape of a spherical segment fix on the wall of a cylindrical central support structure which slides in a circular sleeve fixed on the circular wall of the inner well of an annular peripheral support structure. The geometric center of said spherical segment being on the vertical axis of symmetry common to the two support structures The surface of said protuberance is covered by a stainless and self-lubricating metal, and the wall of the sleeve in contact with the ring is covered with 'a layer of stainless steel.
Selon une autre variante c'est le manchon qui est solidaire du cylindre central au moyen d'une liaison en elastomere, et ledit manchon coulisse sur la paroi interne du puit peripherique, ladite paroi etant en acier inoxydable dans dans les parties sur lesquelles frottent ledit manchon. Les surfaces de friction dudit manchon etant en metal inoxydable auto-lubrifie pour minimiser les frictions. According to another variant, it is the sleeve which is integral with the central cylinder by means of an elastomer connection, and said sleeve slides on the internal wall of the peripheral well, said wall being made of stainless steel in the parts on which said rub muff. The friction surfaces of said sleeve being made of self-lubricating stainless metal to minimize friction.
Selon une autre variante, le moyen de glissement est realise par un ensemble de roues montees sur des pneumatiques et fixees sur l'une des structure-supports. La pression des pneumatiques ainsi que leur nombre sont calcules en fonction de sangle de roulis/tangage desire et de la pression de service de chaque pneumatique. According to another variant, the sliding means is produced by a set of wheels mounted on tires and fixed on one of the support structures. The tire pressures and their number are calculated according to the desired roll / pitch strap and the operating pressure of each tire.
Un moyen de coulissement avec rotation bloque entre les deux parties de la plate-forme est realise par deux bagues horizontales ,decrites ci-dessus, et espacees verticalement le plus possible, pour minimiser les forces qu'elles subissent de la part des moments de roulis et/ou de tangage de la partie peripherique de la plate-forme. A sliding means with blocked rotation between the two parts of the platform is produced by two horizontal rings, described above, and vertically spaced as much as possible, to minimize the forces they undergo from the roll moments and / or pitching of the peripheral part of the platform.
Selon une variante de l'invention5 le coulisseient relatif des deux parties est controle par un mecanisme d'amortissement permettant d'une part d'extraire de l'energie des vagues et d'autre part de controler et de limiter les mouvements de pilonement de second ordre qui sont generes a la periode propre de pilonnement de la partie peripherique. According to a variant of the invention5 the relative sliding of the two parts is controlled by a damping mechanism making it possible on the one hand to extract energy from the waves and on the other hand to control and limit the pounding movements of second order which are generated in the proper period of heaving of the peripheral part.
Selon une variante de l'invention la section de flottaison de la structure-support peripherique est minimisee par l'emploi d'une structure tubulaire dont les tubes sont de faible diametre ,afin de einieiser les forces horizontales de la houle sur ladite structure. Cette structure-support a l'inconveniant de sensibiliser la partie peripherique aux variations de charger. According to a variant of the invention, the flotation section of the peripheral support structure is minimized by the use of a tubular structure whose tubes are of small diameter, in order to einieiser the horizontal forces of the swell on said structure. This support structure has the disadvantage of sensitizing the peripheral part to variations in charge.
Pour remedier a ce problene ladite partie peripherique est ancre par des lignes d'ancrage verticales dont l'elasticite longitudinale est obtenue par l'emploi de ligne en fibres synthetiques, ce qui permet le pilonnement de ladite partie peripherique ,et contribue pour partie a la pre-tension de la plate-forme. To remedy this problem, said peripheral part is anchored by vertical anchoring lines, the longitudinal elasticity of which is obtained by the use of a line of synthetic fibers, which allows the pounding of said peripheral part, and contributes in part to the platform pre-tension.
Selon une variante de l'invention ,la structure-support de la partie centrale est fixee rigidement au flotteur central par un connecteur. Le niveau de la connexion sous la surface de la mer est situe a une profondeur inferieure au tirant d'eau de transit de la plate-forme obtenu par lpevacuation des fluides contenus dans le flotteur peripherique. Un moyen de connexion permet a la structure-support centrale et le pont central qu'elle supporte detre fixes temporairement a la partie peripherique, lorsque la plate-forme flotte a son tirant d'eau minimum. La deconnexion du flotteur central permet par exemple le carenage de la plate-forme, sans avoir a detendre les tendons. According to a variant of the invention, the support structure of the central part is rigidly fixed to the central float by a connector. The level of the connection below the surface of the sea is located at a depth lower than the draft of transit water from the platform obtained by the evacuation of the fluids contained in the peripheral float. A connection means allows the central support structure and the central bridge that it supports to be temporarily fixed to the peripheral part, when the platform floats at its minimum draft. The disconnection of the central float allows for example the fairing of the platform, without having to relax the tendons.
La figure 1 represente schematiquement une coupe verticale axiale d'une plate-forme selon l'invention.Figure 1 shows schematically an axial vertical section of a platform according to the invention.
La figure 2 represente schematiquement la coupe plane et horizontale AA de la plate-forme de la figure 1 et de la figure 5. FIG. 2 schematically represents the flat and horizontal section AA of the platform of FIG. 1 and of FIG. 5.
La figure 3 represente schematiquement, une coupe verticale axiale d'une plate-forme selon l'invention. Figure 3 shows schematically, an axial vertical section of a platform according to the invention.
La figure 4 represente schematiquement, la coupe plane et horizontale BB de la plate-forme de la figure 3. FIG. 4 schematically represents the planar and horizontal section BB of the platform of FIG. 3.
La figure 5 represente schezatiquement, une coupe verticale axiale d'une plate-forme selon l'invention5amenagee pour le stockage et le chargement de petrole, en mer. Figure 5 shows schematically, an axial vertical section of a platform according to the invention5amenagee for the storage and loading of oil, at sea.
La figure 6 represente vue schematique du remorquage de la plate-forme de la figure 5, apres deconnexion de son flotteur central. Figure 6 represents schematic view of the towing of the platform of Figure 5, after disconnection of its central float.
La figure 7 represente schematiquement, une coupe verticale axiale, d'une plate-forme selon l'invention, amenagee en plate-forme de forage-production, avec son reservoir de stockage et son poste de chargement de tanker integres. Figure 7 shows schematically, an axial vertical section of a platform according to the invention, converted into a drilling-production platform, with its storage tank and its integrated tanker loading station.
La figure 8 represente schematiquement, la coupe plane et horizontale CC de la plate-forme de la figure 7. Figure 8 shows schematically, the planar and horizontal section CC of the platform of Figure 7.
La figure 9 represente schematiquezents la coupe plane et horizontale DD de la plate-forme de la figure 7. Figure 9 schematically represents the flat and horizontal section DD of the platform of Figure 7.
La figure 10 represente schematiquement, la coupe plane et horizontale
EE de Ia plate-forme de la figure 7.Figure 10 shows schematically, the planar and horizontal section
EE of the platform of figure 7.
La plate-forme representee schematiquement sur la figure i comporte une partie centrale composee d'un pont cylindrique (1) d' axe vertical,
supporte rigidement sur un flotteur central (3) cylindrique d'axe vertical, immerge par l'intermediaire d'un support (2) semi-immerge cylindrique d'axe vertical. Le pont (1) a des dimensions de l'ordre de 50 metres pour le diametre et de 20 metres pour la hauteur. Le support (2) a des dimensions de 1 'ordre de 35 metres pour le di ametre de 100 metres pour la hauteur, et de 75 metres pour le tirant d'eau en utilisation normale.Les tendons de l'amarrage du flotteur 83) sont des tubes (5) metalliques uniformement repartis et fixes chacun, a la peripherie de la base du flotteur (3) au moyen d'un connecteur hydraulique annulaire (4) semblable a ceux utilises par l'industrie petroliere offshore pour connecter les tubes aux blocs d'obturation des puits sous-marins. Les tubes (5) sont tendus verticalement par le flotteur (3) ,et sont fixes a leur base par un connecteur hydraulique annulaire (4) a une embase gravitaire annulaire (6) , reposant sur le fond de la mer (7). Le poids apparent de l'embase (6) est calcule pour que l'embase (6) reste fixee au fond (7) maigre les tensions variables transmises par les tubes (5). La plate-forme comporte une partie peripherique flottante qui entoure la partie centrale. Les deux parties possedent toute deux le meme axe vertical de symetrie. La partie peripherique comporte un pont peripherique (8) en forme d'anneau cylindrique, supporte rigidement sur un flotteur peripherique cylindrique.Le pont (8) a des dimensions de l'ordre de 140 metres pour le diametre exterieur, de 90 metres pour le diametre interieur et de 20 metres pour la hauteur.The platform represented diagrammatically in FIG. I comprises a central part composed of a cylindrical bridge (1) of vertical axis,
rigidly supported on a central cylindrical float (3) with vertical axis, immersed by means of a semi-submerged cylindrical support (2) with vertical axis. The bridge (1) has dimensions of the order of 50 meters for the diameter and 20 meters for the height. The support (2) has dimensions of the order of 35 meters for the diameter of 100 meters for the height, and of 75 meters for the draft in normal use. The tendons of the mooring of the float 83) are metallic tubes (5) uniformly distributed and fixed each, around the base of the float (3) by means of an annular hydraulic connector (4) similar to those used by the offshore petroleum industry to connect the tubes to blockages for submarine wells. The tubes (5) are stretched vertically by the float (3), and are fixed at their base by an annular hydraulic connector (4) to an annular gravity base (6), resting on the bottom of the sea (7). The apparent weight of the base (6) is calculated so that the base (6) remains fixed to the bottom (7) lean the variable tensions transmitted by the tubes (5). The platform has a floating peripheral part which surrounds the central part. The two parts both have the same vertical axis of symmetry. The peripheral part comprises a peripheral bridge (8) in the form of a cylindrical ring, rigidly supported on a peripheral cylindrical float. The bridge (8) has dimensions of the order of 140 meters for the outside diameter, 90 meters for the inside diameter and 20 meters for height.
Le flotteur peripherique (10) a la forme d'un recipient cylindrique a parois epaisses ,sans fond, ferme par un couvercle circulaire epais (11) munis d'un orifice central (12) circulaire, d'axe vertical. L'orifice (12) est obture par le support (2), qui y coulisse au travers au moyen d'une bague (13) en forme d'anneau spherique, centre sur l'axe de symetrie de la plate-forme, et qui est solidaire du support t2) La bague (13) obture l'espace annulaire situee entre la paroi de l'orifice central (12) et la paroi cylindrique du support central (2). La bague (13) frotte sur ladite paroi cylindrique.Elle est recouverte d'une garniture métallique auto-lubrifiante ,et les parties de ladite paroi, pouvant etre au contact de la bague sont recouvertes d'intox 31L. The peripheral float (10) has the shape of a cylindrical container with thick walls, bottomless, closed by a thick circular cover (11) provided with a central orifice (12) circular, of vertical axis. The orifice (12) is closed by the support (2), which slides there through by means of a ring (13) in the form of a spherical ring, center on the axis of symmetry of the platform, and which is integral with the support t2) The ring (13) seals the annular space located between the wall of the central orifice (12) and the cylindrical wall of the central support (2). The ring (13) rubs against said cylindrical wall. It is covered with a self-lubricating metal lining, and the parts of said wall, which may be in contact with the ring, are covered with 31L stainless steel.
Le flotteur peripherique (10) sans fond forme une cavite (14) cylindrique, dont l'ouverture est orientez vers le fond de la mer. Cette cavite a des dimensions de l'ordre de 90 metres pour la hauteur, de 80 metres pour le diametre ,et son volume est de l'ordre du deplacement de ses parois. The bottomless peripheral float (10) forms a cylindrical cavity (14), the opening of which is oriented towards the bottom of the sea. This cavity has dimensions of the order of 90 meters for the height, 80 meters for the diameter, and its volume is of the order of the displacement of its walls.
Le tirant d'eau de la plate-forme est celui du flotteur (10) qui est de l'ordre de 140 metres. Le couvercle < 11) est compartimente en deux compartiments annulaires coaxiaux un compartiment-flotteur (18) et un compartiment-ballast (19), ce dernier servant a equilibrer le deplacement du flotteur (10) ,en fonction de la quantite de petrole stocke dans le reservoir (42), que forme la partie annulaire cylindrique du flotteur peripherique (10). Le stockage du petrole s'y effectue, selon le principe de la cloche renversee. C'est-a-dire que le reservoir (42) est en permanence en communication avec la mer a sa partie inferieure. Le petrole ayant une densite approximative de .875, deplace l'eau de mer dans la partie haute du reservoir (42). The draft of the platform is that of the float (10) which is of the order of 140 meters. The cover <11) is divided into two coaxial annular compartments, a float compartment (18) and a ballast compartment (19), the latter serving to balance the displacement of the float (10), as a function of the quantity of oil stored in the reservoir (42), which forms the cylindrical annular part of the peripheral float (10). The oil is stored there, according to the principle of the inverted bell. That is to say that the reservoir (42) is permanently in communication with the sea at its lower part. The petroleum having an approximate density of .875, displaces seawater in the upper part of the tank (42).
L'ensemble du flotteur peripherique est munis de cloisons radiales planes, etanches (38), qui sont repartis uniformement dans le flotteur (10). The entire peripheral float is provided with planar, watertight radial partitions (38), which are distributed uniformly in the float (10).
Le support peripherique (9) est realise par un ensemble de tubes metalliques verticaux a moitie immerges, repartis uniformement sur la peripherie du couvercle (11). Leur faible section minimise les forces des vagues, mais rend la partie peripherique sensible aux variations de charge ,car cell -ci produisent une modification importante du tirant d'eau.Afin de pallier a cet inconveniant ,un ensemble de lignes elastiques (17) sont tendues en pre-tension entre la base annulaire du flotteur peripherique (10) et des ancres (15) fixes sur le fond de la mer (7). Le coefficient d'elasticite de l'ensemble des lignes est calcule de facon r etre équivalent au coefficient d'elasticite produit par la section droite de flottaison qui manque au support (9) .The peripheral support (9) is produced by a set of vertical metal tubes, half immersed, distributed uniformly on the periphery of the cover (11). Their small section minimizes the wave forces, but makes the peripheral part sensitive to load variations, because these produce a significant modification of the draft. To overcome this inconvenience, a set of elastic lines (17) are tensioned in pre-tension between the annular base of the peripheral float (10) and anchors (15) fixed on the seabed (7). The coefficient of elasticity of all the lines is calculated in such a way as to be equivalent to the coefficient of elasticity produced by the straight section of flotation which is missing from the support (9).
La distance horizontale separant les tendons (5) verticaux, de la paroi verticale interieure de la cavite (14) est d'environ 15 metres, ce qui permet une inclinaison maximale des tendons de l'ordre de 10 degres, avant que ceux-ci viennent toucher la base du flotteur peripherique (10), quand ce dernier est incline d'environ 5 degres. La partie peripherique a son centre de gravite 6, etabli a quelques metres en-dessous de son centre de flottaison
B ,au moyen d'un lest 816) annulaire installe dans la base du son flotteur (10). The horizontal distance separating the vertical tendons (5) from the interior vertical wall of the cavity (14) is approximately 15 meters, which allows a maximum inclination of the tendons of the order of 10 degrees, before these come to touch the base of the peripheral float (10), when the latter is inclined by about 5 degrees. The peripheral part at its center of gravity 6, established a few meters below its center of flotation
B, by means of an annular ballast 816) installed in the base of the float sound (10).
Dans la forme de realisation selon la figure 3, la plate-forme est symetrique selon un axe vertical de symetrie. Cette plate-forme differt de par sa forme de celle de la figure 1 mais son utilisation est identique. In the embodiment according to Figure 3, the platform is symmetrical along a vertical axis of symmetry. This platform differs in its form from that of Figure 1 but its use is identical.
Elle sert de stockage petrolier flottant. La forme de son flotteur peripherique se prete a une construction en beton. La partie centrale comprend un pont central (1) en forme de cone tronque, evase vers son sommet et qui'est
supporte rigidemment sur un flotteur central immerge conique t 3) par lsintermediaire dsun support cylindrique (2) semi-immerge. L'amarage est.It serves as floating oil storage. The shape of its peripheral float lends itself to a concrete construction. The central part includes a central bridge (1) in the shape of a truncated cone, flared towards its top and which is
rigidly supported on a conical immersed central float t 3) via a semi-immersed cylindrical support (2). The mooring is.
realise par un ensemble de tendons verticaux (5) disposes a la peripherie de la base du flotteur central (3) et fixes chacun au moyen d'un connecteur hydraulique (4). La partie peripherique de la plate-forme comprend un pont annulaire (8) entourant a une dizaine de metres, environ le pont (1). Un support conique (9) en partie immerge a sa base, est fixe sur la partie haute annulaire du couvercle conique (11) du flotteur peripherique (10) La partie peripherique presente ainsi une section de flottaison minimale, qui s'accroit de part et d'autre lorsque ladite partie pilonne. Cette propriete est mise a profit pour-degager la plate-forme de l'emprise des glaces, dans les regions polaires.Le pilonnement est alors provoque par la variation lente de la charge de la partie peripherique, en variant les quantites d'eau stockees dans les compartiments-ballast (19). Le flotteur peripherique (10) forme un recipient sans fond et presente un grand orifice (12) au centre de son couvercle conique (11), dans lequel coulisse le support central (2).produced by a set of vertical tendons (5) disposed at the periphery of the base of the central float (3) and fixed each by means of a hydraulic connector (4). The peripheral part of the platform comprises an annular bridge (8) surrounding at about ten meters, approximately the bridge (1). A conical support (9) partly submerged at its base, is fixed on the annular upper part of the conical cover (11) of the peripheral float (10) The peripheral part thus has a minimum flotation section, which increases in part and else when said part pounded. This property is used to clear the ice grip platform in the polar regions. The heaving is then caused by the slow variation of the load of the peripheral part, by varying the quantities of water stored. in the ballast compartments (19). The peripheral float (10) forms a bottomless container and has a large orifice (12) in the center of its conical cover (11), in which the central support (2) slides.
Le coulissement est realise au moyen d'une bague cylindrique(21) fixee au support central (2), au moyen d'une serie de patins en caoutchouc inseres entre deux coques concentriques metalliques ,dont le centre est situe sur l'axe dé symetrie de la plate-forme. Chaque patin est compose par un sandwich de couches de plaques metalliques et de caoutchouc naturel, colles ensemble par vulcanisation. La bague (21) coulisse en frottant sur les parois du puit cylindrique d'axe vertical,compose dans sa partie basse par orifice (12) et dans sa partie superieure par le puit central du support peripherique (). The sliding is carried out by means of a cylindrical ring (21) fixed to the central support (2), by means of a series of rubber pads inserted between two concentric metal shells, the center of which is situated on the axis of symmetry of the platform. Each skate is made up of a sandwich of layers of metal plates and natural rubber, glued together by vulcanization. The ring (21) slides by rubbing on the walls of the cylindrical well of vertical axis, composed in its lower part by orifice (12) and in its upper part by the central well of the peripheral support ().
Le couvercle (11) comprend un compartiment-flotteur (18) et un compartiment-ballast (19). La partie annulaire cylindrique du flotteur (10) qui forme reservoir est realise par un ensemble jointif de cylindres-reservoirs (43) dont les axes verticaux sont repartis sur un meme cercle horizontal, et dont les bases (22) sont en forme de calotte spherique et dont les toits (23) sont coniques. Un lest annulaire est realise par de la baryte logee dans les bases des cylindres (43). The cover (11) includes a float compartment (18) and a ballast compartment (19). The cylindrical annular part of the float (10) which forms a reservoir is produced by a contiguous assembly of cylinder-reservoirs (43) whose vertical axes are distributed on the same horizontal circle, and whose bases (22) are in the form of a spherical cap and whose roofs (23) are conical. An annular ballast is produced by barite housed in the bases of the cylinders (43).
Dans la forme de realisation selon la figure 5 ,la plate-forme est une plate-forme de stockage et de chargement pour petrolier, qui possède un axe vertical de symetrie. In the embodiment according to Figure 5, the platform is a storage and loading platform for tanker, which has a vertical axis of symmetry.
La partie centrale comprend un pont central {1) circulaire qui repose sur un support central (2) ,qui est un cylindre de meme diametre que le pont (1). Le support central (2) est fixe sur un flotteur en forme de cone tronque (3) au moyen d'un systeme de connexion rigide (33). Des tendons (5) sont regulierement fixes sur le pourtour de la base du flotteur (3) ils sont tendus verticalement et fixes par des connecteurs (4) a une embase annulaire (6) elle-eme fixee sur le fond (7) au moyen de pieux fores (34). The central part includes a circular central bridge (1) which rests on a central support (2), which is a cylinder of the same diameter as the bridge (1). The central support (2) is fixed to a truncated cone-shaped float (3) by means of a rigid connection system (33). Tendons (5) are regularly fixed on the periphery of the base of the float (3) they are stretched vertically and fixed by connectors (4) to an annular base (6) itself fixed on the bottom (7) by means bored piles (34).
La partie peripherique de la plate-forme comprend un pont (8), un support annulaire cylindrique (9) a deii-i-erge, dont la base repose sur le sommet du toit conique tronque (11) du flotteur peripherique (10), qui est
cylindrique et annulaire (10) Ce flotteur (10) forme une cavite (14) cylindrique entierement ouverte a sa partie inferieure. Le flotteur central conique (3) est place'dans la partie superieure conique de la cavite (14).The peripheral part of the platform comprises a bridge (8), a cylindrical annular support (9) a deii-i-erge, the base of which rests on the top of the truncated conical roof (11) of the peripheral float (10), who is
cylindrical and annular (10) This float (10) forms a cylindrical cavity (14) entirely open at its lower part. The conical central float (3) is placed in the upper conical part of the cavity (14).
Le flotteur central (3) est place de facon a ne pas toucher le toit 811), durant le pilonement extreme de la partie peripherique lorsqu'elle coulisse verticalement le long et autour du support central (2). Le coulissement est assure par deux bagues circulaires (40) et (41) fixees a la paroi circulaire du puit interne vertical du support peripherique (9). L'espacement vertical des deux bagues est maximise pour minimiser les forces produites dans les bagues, par les moments de roulis et/ou de
tangage transmis par la partie peripherique a la partie centrale, dont par construction, les mouvements de roulis et de tangage sont bloques par les tendons (5) de l'amarrage de la plate-forme.Le pont central (1) est situe au-dessus du niveau des plus hautes vagues qui passent par la base ouverte du flotteur peripherique (10) Cc niveau est inferieur a celui qui prevaut a l'exterieur de la plate-forme , a cause de l'attenuation exponentielle des pressions hydrodynamiques des vagues avec la profondeur.La partie peripherique de la plate-forme comprend un pont (8) équipe en son centre d'un joint articule (27) auquel est fixe par en-dessous un flexible en forme d'omega dont l'autre extremite est connectee par un connecteur annulaire (4) a un tube petrolier (35) qui traverse verticalement et M en soncentre le support (2) ,ledit tube (35) etant lui- z connecte par un connecteur (4) a un tube petrolier (36) du flotteur central (3). Le flexible (28) en forme de omega incline a 90 degre, absorbe les variations de distance entre les deux parties de la plate-forme, dues
au pilonnement relatif de la partie peripherique et du pont central (1) dont le pilonnement est bloque par les tendons (5). The central float (3) is placed so as not to touch the roof 811), during the extreme pounding of the peripheral part when it slides vertically along and around the central support (2). The sliding is ensured by two circular rings (40) and (41) fixed to the circular wall of the vertical internal well of the peripheral support (9). The vertical spacing of the two rings is maximized to minimize the forces produced in the rings, by the moments of roll and / or
pitch transmitted by the peripheral part to the central part, which by construction, the movements of roll and pitch are blocked by the tendons (5) of the mooring of the platform. The central bridge (1) is located at above the level of the highest waves passing through the open base of the peripheral float (10) This level is lower than that prevailing outside the platform, due to the exponential attenuation of the hydrodynamic pressures of the waves with The peripheral part of the platform includes a bridge (8) fitted in its center with an articulated joint (27) to which is fixed from below a flexible omega-shaped whose other end is connected by an annular connector (4) to a petroleum tube (35) which passes vertically and M in its center the support (2), said tube (35) being itself connected by a connector (4) to a petroleum tube (36) of the central float (3). The omega-shaped hose (28) tilts 90 degrees, absorbs variations in distance between the two parts of the platform, due to
the relative heaving of the peripheral part and the central bridge (1), the heaving of which is blocked by the tendons (5).
Lors du chargement d'un tanker, le petrole provient soit du reservoir (42) du flotteur peripherique (10) ,soit directement de la plate-forme de production associe a la plate-forme de stockage ,au moyen d'une conduite sous-marine (32) posee sur le fond de la mer (7). L'un des tendons est un tube petrolier (24) utilise pour remonter le petrole du fond de la mer, jusqu'au flotteur central ou il penetre en passant par le connecteur annulaire (4) du tube (24). Le petrole traverse le flotteur central (3) par le tube (36), et passe dans le tube < 35) du support central (2), au moyen d'un connecteur (4). Le tube (35) debouche au centre du sommet du support central (2) ou il est connecte au flexible t28) par un connecteur (4). When loading a tanker, the oil comes either from the tank (42) of the peripheral float (10), or directly from the production platform associated with the storage platform, by means of a sub-line marine (32) placed on the bottom of the sea (7). One of the tendons is a petroleum tube (24) used to raise the oil from the bottom of the sea, to the central float where it penetrates via the annular connector (4) of the tube (24). The oil passes through the central float (3) through the tube (36), and passes through the tube <35) of the central support (2), by means of a connector (4). The tube (35) opens out at the center of the top of the central support (2) where it is connected to the flexible t28) by a connector (4).
Lorsque la plate-forme ne renferme pas de petrole, son reservoir (42) est rempli par d'eau de mer, qui penetre au travers d'un filtre (37) installe a la base du flotteur peripherique (10). Lorsque du petrole arrive de la plate-forme de production, par la ligne (32), ce petrole est dirige a travers le manifold (35) vers le reservoir (42) au moyen de la conduite (36) qui debouche au sommet du reservoir (42) en descendant a l'interieur du support (9) et du toit conique (11). Le petrole stocke, d place progressivement l'eau de mer ,qui est rejeter a l'exterieur apres avoir ete prealablement nettoyee par le filtre (37). La densite du petrole etant d'environ .875 contre 1.025 pour l'eau de mr, il est necessaire de remplir progressivement le compartiment ballast < 19) d'eau de mer pour compenser la différence de densite des fluides stockes et maintenir constant le tirant d'eau de service de la partie peripherique.Le reservoir (42) est compartimente au moyen de cloisons verticales (38) radiales etanches ,regulierement espacees dont la fonction est de stabiliser le niveau de l'interface petrole-mau lorsque la plate-forme est deplacie par la houle. De plus ces cloisons radiales (38) limitent les fuites en cas de percement accidentel du reservoir (42). When the platform does not contain oil, its reservoir (42) is filled with sea water, which penetrates through a filter (37) installed at the base of the peripheral float (10). When oil arrives from the production platform, through the line (32), this oil is directed through the manifold (35) to the tank (42) by means of the pipe (36) which opens at the top of the tank (42) descending inside the support (9) and the conical roof (11). The stored oil gradually displaces the sea water, which is discharged to the outside after having been previously cleaned by the filter (37). The density of the oil being about .875 against 1.025 for the mr water, it is necessary to gradually fill the ballast compartment <19) of sea water to compensate for the difference in density of the stored fluids and keep the draft constant service water of the peripheral part. The reservoir (42) is compartmentalized by means of vertical radial bulkheads (38), regularly spaced, the function of which is to stabilize the level of the oil-oil interface when the platform is displaced by the swell. In addition, these radial partitions (38) limit leaks in the event of accidental piercing of the reservoir (42).
Des cloisons verticales radiales et etanches (39) divisent egalement l'ensemble du toit (11) et du support peripherique (9) pour des raisons structurelles et de securite. Radial and sealed vertical partitions (39) also divide the assembly of the roof (11) and the peripheral support (9) for structural and safety reasons.
Le coulissement sans rotation d'axe horizontal entre les deux parties de la plate-forme est realise par deux bagues t40) et (41), regulierement segmentees en patins fixes sur la paroi circulaire du puit interieur. La section droite des patins est en demi-cercle, et la surface de friction des patins est recouverte d'une garniture metallique auto-lubrifiante. Les parties de la paroi du support t2) devant rentrer on contact avec les patins sont eux recouverts d'une couche d'inox 316 L. The sliding without rotation of a horizontal axis between the two parts of the platform is achieved by two rings t40) and (41), regularly segmented into fixed shoes on the circular wall of the interior well. The cross-section of the skids is in a semicircle, and the friction surface of the skids is covered with a self-lubricating metal lining. The parts of the wall of the support t2) which must come into contact with the pads are themselves covered with a layer of 316 L stainless steel.
L'installation de la plate-forme s'effectue en deux temps. Le flotteur central (3) est d'abord installe, avec ses tendons et son embase (6), a l'aide de supports de surface classiques. Un systeme de ballastage et de vidange du flotteur (2) permet l'immersion, la mise en place des tendons (5) et du tube (24), ainsi que leur mise en tension. Puis la plate-forme est remorquee en flottaison au-dessus du flotteur central (3) immerge. Le remplissage progressif de son reservoir avec de l'eau de mer,-fait descendre progressivement le support central (2) a la verticale du flotteur central (3) ,jusqu'a ce que la connexion par le systeme (33) soit realisee. Le connecteur (4) reliant les tubes (35) et (36) est ensuite actionne.Pour faciliter la connexion de la plate-forme, la flottabilite du support central (2) est limitee par inondation partielle temporaire avec de l'eau de mer. The platform is installed in two stages. The central float (3) is first installed, with its tendons and its base (6), using conventional surface supports. A ballasting and emptying system of the float (2) allows the immersion, the positioning of the tendons (5) and the tube (24), as well as their tensioning. Then the platform is towed floating above the immersed central float (3). The gradual filling of its reservoir with sea water, -spread the central support (2) gradually down the vertical of the central float (3), until the connection by the system (33) is made. The connector (4) connecting the tubes (35) and (36) is then actuated. To facilitate the connection of the platform, the buoyancy of the central support (2) is limited by temporary partial flooding with sea water .
Dans la forme de realisation selon la figure 7, la plate-forme possede un axe vertical de symetrie. Cette plate-forme est utilisee comme plate-forme de forage-production. In the embodiment according to Figure 7, the platform has a vertical axis of symmetry. This platform is used as a drilling-production platform.
Elle est equipee d'un stockage t42) et d'un poste de chargement pour tanker (53 > . Sa partie centrale comporte un pont (1), rigidement fixe sur un flotteur central (3) par un support semi-immerge (2). Le support (2) est en forme d'anneau cylindrique et il est emmanche dans une cavite cylindrique -situee dans le sommet tronque du flotteur (3) de forme conique. Le flotteur est ancre au moyen de tendons (5) realises par des tubes metalliques de grande raideur longitudinale. Les tendons sont repartis uniformement sur le pourtour de la base du flotteur (3) ,ou ils sont connectes au moyen de connecteurs (4 > . It is equipped with a storage t42) and a loading station for tanker (53>. Its central part includes a bridge (1), rigidly fixed on a central float (3) by a semi-submerged support (2) The support (2) is in the form of a cylindrical ring and is fitted into a cylindrical cavity - located in the truncated top of the conical float (3). The float is anchored by means of tendons (5) made by metal tubes of great longitudinal stiffness The tendons are distributed uniformly around the base of the float (3), or they are connected by means of connectors (4>.
La paroi externe et la paroi interne du support central (2) sont connectees a leur base au flotteur (3) de facon etanche au moyen de systemes de connexion annulaires (52). Un ensemble de risers verticaux (47) repartis uniformement en cercle, remontent de puits sous-marins -jusqu'a leurs tetes de production respectives (49) installees sur un pont de production annulaire (54) , situe a l'interieur du support (2). Ces risers passent au travers du flotteur central (3) au moyen de puits verticaux (51), dont la forme evasee vers le bas ,en forme de trompette, impose au riser une courbure optimale, lors des excursions horizontales de la plate-forme, ce qui minimise les contraintes internes desdits risers.L'extremite superieure de chacun des puits (51) est obturee de facon etanche par une tete de production sous-marine (50) fixee au flotteur central et qui connecte la partie superieure de chaque riser situee dans le support (2), a avec sa partie inferieure de riser correspondante. Chaque riser possede ainsi deux tetes de production. La tete sous-marine (50) etant utilise lorsque le support central (2) est deconnecte du flotteur (3 > . La d connexion s'effectue en deconnectant les connecteurs (52) et (SO) Deux derricks (48), installes sur le pont (1), servent au forage et a l'entretien des puits de production.Ces derricks (48) sont montes sur un circuit de rails circulaires pour pouvoir chacun se positionner a la verticale de chaque riser. The outer wall and the inner wall of the central support (2) are connected at their base to the float (3) in a sealed manner by means of annular connection systems (52). A set of vertical risers (47) distributed uniformly in a circle, rising from underwater wells -up to their respective production heads (49) installed on an annular production bridge (54), located inside the support ( 2). These risers pass through the central float (3) by means of vertical wells (51), whose shape flared downwards, in the shape of a trumpet, imposes on the riser an optimal curvature, during the horizontal excursions of the platform, which minimizes the internal stresses of said risers. The upper end of each of the wells (51) is sealed off by an underwater production head (50) fixed to the central float and which connects the upper part of each riser located in the support (2), has with its corresponding lower riser part. Each riser thus has two production heads. The underwater head (50) being used when the central support (2) is disconnected from the float (3>. The connection is made by disconnecting the connectors (52) and (SO) Two derricks (48), installed on the bridge (1), are used for drilling and maintenance of production wells. These derricks (48) are mounted on a circuit of circular rails so that each can be positioned vertically on each riser.
La partie peripherique de la plate-forme comprend un petit pont annulaire (8) installe sous le pont central (1 > . Le support peripherique (9) est en forme d'anneau cylindrique a deai-immerge dans sa partie haute et dans sa partie inferieure, il est en forme de cone dont le sommet tronque a me diametre que la base de l'anneau cylindrique auquel il se raccorde par son sommet
L'une des characteristiques principales de l'invention, selon le schema de la figure 7, est la forme du flotteur peripherique (10), qui a la forme d'un dome d'epaisseur a peu pres
constante, et dont le centre geometrique est situe au-dessus de l'ouverture de sa base plane a environ 35% de la hauteur de la cavite (14) qu'il defini. The peripheral part of the platform includes a small annular bridge (8) installed under the central bridge (1>. The peripheral support (9) is in the form of a cylindrical ring with deai-immersed in its upper part and in its part lower, it is cone-shaped, the truncated top of which is the same diameter as the base of the cylindrical ring to which it is connected by its top
One of the main characteristics of the invention, according to the diagram in FIG. 7, is the shape of the peripheral float (10), which has the shape of a dome of thickness approximately
constant, and whose geometric center is located above the opening of its flat base at about 35% of the height of the cavity (14) that it defines.
La partie haute du dome est tronque selon un plan horizontal qui ne tronque pas la cavite (14). La partie circulaire du dome tronque a meme diametre que la base conique du support peripherique (9) et a laquelle, elle se raccorde
Le sommet du flotteur < 10) est perce en son centre d'un orifice d'axe vertical dont le diametre d'environ 35 metres est egal a celui de l'espace cylindrique forme par le support annulaire (9). Ainsi l'orifice (12) est le prolongement dudit espace annulaire du support (9) ce qui permet au support de la partie centrale d'y coulisser.La forme du flotteur peripherique peut etre decrite comme etant celle d'un recipient sphérique sans fond, dont le couvercle est
defini par la partie du flotteur (10) situe verticalement sous la partie inferieure conique du support peripherique (9). Le couvercle ainsi defini, se divise en deux compartiments annulaires etanches coaxiaux, imbriques l'un dans l'autre ;un compartiment-ballast < 19) et un compartiment-flotteur < 18)
Les deux compartiments (18) et (19) sont tous deux compartimentes par des cloisons planes radiales etanches (39). Le reste du flotteur (0), qui forme un reservoir (42) utilise pour le stockage du petrole, est lui
aussi compartimente par des cloisons radiales étanches < 38). Lorsque la plate-forme flotte a son tirant d'eau de service, le reservoir < 42)
est constamment rempli de petrole et/ou d'eau de mer. La variation de densite du volume du fluide stocke est corrigee par un ballast variable d'eau de mer introduit dans le compartiment-ballast (19). The upper part of the dome is truncated along a horizontal plane which does not truncate the cavity (14). The circular part of the dome truncates to the same diameter as the conical base of the peripheral support (9) and to which it is connected
The top of the float <10) is pierced in its center with an orifice with a vertical axis whose diameter of about 35 meters is equal to that of the cylindrical space formed by the annular support (9). Thus the orifice (12) is an extension of said annular space of the support (9) which allows the support of the central part to slide therein. The shape of the peripheral float can be described as being that of a bottomless spherical container , whose cover is
defined by the part of the float (10) situated vertically under the conical lower part of the peripheral support (9). The cover thus defined is divided into two annular watertight coaxial compartments, nested one inside the other; a ballast compartment <19) and a float compartment <18)
The two compartments (18) and (19) are both divided by planar radial watertight partitions (39). The rest of the float (0), which forms a reservoir (42) used for the storage of oil, is it
also compartmentalized by watertight radial bulkheads <38). When the platform floats with its service draft, the tank <42)
is constantly filled with petroleum and / or seawater. The variation in density of the volume of the stored fluid is corrected by a variable ballast of seawater introduced into the ballast compartment (19).
Le diametre externe du flotteur (10) est d'environ 140 metres et son tirant d'eau de service est d'environ 115 metres. Le volume du flotteur (10) est approximativement egal au volume de la cavite (14). The external diameter of the float (10) is approximately 140 meters and its working water draft is approximately 115 meters. The volume of the float (10) is approximately equal to the volume of the cavity (14).
Les parois externes et internes du flotteur (10) sont approximees au moyen de panneaux plans trapezoidaux dont la plus grande dimension est approximativement egale a l'epaisseur du dome spherique repais, wr les surfaces duquel sont localises les sommets des panneaux. The external and internal walls of the float (10) are approximated by means of trapezoidal flat panels, the largest dimension of which is approximately equal to the thickness of the repressed spherical dome, wr the surfaces of which the vertices of the panels are located.
Le flotteur central t3) est situe au-dessus du centre gel trique O du flotteur peripherique (10) dans la partie haute de la cavite (14) OU le support (2)
penetre par l'orifice (12). La partie peripherique protege la partie centrale des pressions directes des vagues, dont l'influence se fait sentir que par passage par l'ouverture circulaire de la base du flotteur (10).The central float t3) is located above the freezing center O of the peripheral float (10) in the upper part of the cavity (14) OR the support (2)
enter through the orifice (12). The peripheral part protects the central part from direct wave pressures, the influence of which is felt only by passing through the circular opening of the base of the float (10).
Commue l'amortissement des pressions de la houle d croit exponentiellement, la protection de la partie peripherique est considerable. As the damping of the wave pressures increases exponentially, the protection of the peripheral part is considerable.
De plus comme la tres grande majorite des lignes d'action des pressions hydrodynamiques qui s'exercent sur le flotteur (10) convergent et passent au travers d'une petite zone geoeetrique (46) spheroidale dont le diametre est approximativement egal a l'epaisseur moyenne du flotteur (10), les moments de roulis et de tangage auxquels s'opposent les tendons sont peu importants relativement a ceux produit par les flotteurs peripheriques des plate-formes des figures 1,3,et 5. In addition, as the very great majority of the lines of action of the hydrodynamic pressures which are exerted on the float (10) converge and pass through a small spheroidal geo-electric zone (46) whose diameter is approximately equal to the thickness mean of the float (10), the moments of roll and pitch which the tendons oppose are of little importance relative to those produced by the peripheral floats of the platforms of Figures 1,3, and 5.
Le centre de gravite G de la partie peripherique est situe sous son centre de flottaison B, mais au-dessus du centre geometrique 0 La position du centre de gravite est obtenu par un lest (16) installe dans la base du flotteur (10). Ce lest est constitue par du beton. The center of gravity G of the peripheral part is located under its center of buoyancy B, but above the geometric center 0 The position of the center of gravity is obtained by a ballast (16) installed in the base of the float (10). This ballast is made up of concrete.
Les moments de roulis et de tangage qu'exerce la houle sur le flotteur peripherique (10) relativement au
centre de gravite G de la partie peripherique, sont de signe contraire a ceux que la houle exerce sur le support peripherique (9). Cette opposition des moments
reduit d'autant les reactions dynamiques dans les tendons.The rolling and pitching moments exerted by the swell on the peripheral float (10) relative to the
center of gravity G of the peripheral part, are of opposite sign to those that the swell exerts on the peripheral support (9). This opposition of moments
reduces the dynamic reactions in the tendons accordingly.
Le coulissement de la partie peripherique autour de la partie centrale est realise au moyen d'un ensemble de bagues (52) similaires aux bagues de la plate-forme de la figure 5. De meme les parties du support central (2) sur lesquelles frottent les segments des bagues < 52), sont recouvertes d'inox 316L. The sliding of the peripheral part around the central part is carried out by means of a set of rings (52) similar to the rings of the platform of FIG. 5. Likewise the parts of the central support (2) on which rub the ring segments <52) are covered with 316L stainless steel.
Un ensemble de puits verticaux etroits (45) traversent la partie superieure du reservoir (42). Chaque puit (45) est dispose a la vertical d'un connecteur de tendon (4) installe sur le pourtour de la base du flotteur central. Cette disposition des puits (45), permet le relevage et/ou l'installation d'un tendon a partir du pont (1). A set of narrow vertical wells (45) pass through the upper part of the reservoir (42). Each well (45) is arranged vertically with a tendon connector (4) installed around the periphery of the base of the central float. This arrangement of the wells (45) allows the lifting and / or installation of a tendon from the bridge (1).
Un systeme de chargement en mer de tanker (53) est installe sur le pont (8) et la partie superieure du support (9). Il comprend un flexible de chargement et son tambour de -stockage, ainsi qu'un systeme d'aussieres pour l'amarrage du tanker. Par tension de ltaussiere, le tanker peut orienter le systeme de chargement (53) sous le vent. La rotation de la partie peripherique autour de la partie centrale est aussi obtenuee par deux propulseurs marins (55) diametralement fixes sur la paroi. externe de la base du flotteur peripherique (10). A tanker loading system at sea (53) is installed on the deck (8) and the upper part of the support (9). It includes a loading hose and its storage drum, as well as a hawser system for mooring the tanker. By tension of the tail, the tanker can orient the loading system (53) downwind. The rotation of the peripheral part around the central part is also obtained by two marine thrusters (55) diametrically fixed on the wall. external of the base of the peripheral float (10).
La deconnexion du support central (2) d'avec le flotteur central (3) permet apres fixation du support t2) au support t9) par un moyen approprie, de reduire le tirant d'eau de la partie peripherique par vidange des fluides contenus dans le reservoir (42),jusqu'a ce que la plate-forme arrive a un tirant d'eau de transit, inferieur a la profondeur doimmersion de la partie superieure du flotteur central immerge.Cette manoeuvre permet de degager le flotteur de la cavite (14). La manoeuvre inverse permet de re-amarrer la plate-forme
Le dispositif de deconnexion permet de pre-installer le flotteur central t2) les tendons (5), et les parties inferieures des risers (5) équipe s de leur tete de production sous-marines (50) respectives, durant la periode de construction de la plate-forme.The disconnection of the central support (2) from the central float (3) allows, after fixing of the support t2) to the support t9) by an appropriate means, to reduce the draft of the peripheral part by draining the fluids contained in the reservoir (42), until the platform reaches a transit draft, less than the immersion depth of the upper part of the immersed central float. This maneuver allows the float to be released from the cavity ( 14). The reverse maneuver allows to re-moor the platform
The disconnection device makes it possible to pre-install the central float t2) the tendons (5), and the lower parts of the risers (5) fitted with their respective underwater production heads (50), during the construction period of the platform.
Ce dispositif permet aussi d'equiper un champ petrolier important de plusieurs flotteurs centraux immerges, et desservis alternativement ,pir une seule plate-forme. La production des risers des flotteurs centraux auxquels la plate-forme n'est pas ancree redescend au fond de mer par une conduite
puis est dirigee vers le flotteur central auquel est ancre la plate-forme.This device also makes it possible to equip a large oil field with several submerged central floats, and served alternately, for a single platform. The production of the risers of the central floats to which the platform is not anchored descends to the sea bottom by a pipe
then is directed towards the central float to which the platform is anchored.
Lorsque la plate-forme est en deplacement entre deux flotteurs centraux, la production de l'ensemble des puits est soit arretee monentanerent, soit dirigee vers une petite unite de production temporaire ancree a un des flotteurs centraux du champ. When the platform is moving between two central floats, the production of all the wells is either stopped altogether, or directed to a small temporary production unit anchored to one of the central floats in the field.
La plate-forme selon l'invention est particulierement destinee pour l'extraction des hydrocarbures en mer. The platform according to the invention is particularly intended for the extraction of hydrocarbons at sea.
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8418863A FR2574367A1 (en) | 1984-12-07 | 1984-12-07 | Marine structure with vertical taut anchoring. |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8418863A FR2574367A1 (en) | 1984-12-07 | 1984-12-07 | Marine structure with vertical taut anchoring. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| FR2574367A1 true FR2574367A1 (en) | 1986-06-13 |
Family
ID=9310445
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| FR8418863A Withdrawn FR2574367A1 (en) | 1984-12-07 | 1984-12-07 | Marine structure with vertical taut anchoring. |
Country Status (1)
| Country | Link |
|---|---|
| FR (1) | FR2574367A1 (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2613315A1 (en) * | 1987-04-02 | 1988-10-07 | Frelat Eric | Rotation, translation on the dynamics of a secured insubmergible volume |
| WO1997047515A1 (en) * | 1996-06-11 | 1997-12-18 | Jenan Kazim | Improved tethered marine stabilising system |
| US5983822A (en) | 1998-09-03 | 1999-11-16 | Texaco Inc. | Polygon floating offshore structure |
| US6230645B1 (en) | 1998-09-03 | 2001-05-15 | Texaco Inc. | Floating offshore structure containing apertures |
| US6712560B1 (en) | 2000-12-07 | 2004-03-30 | Fmc Technologies, Inc. | Riser support for floating offshore structure |
| WO2004074086A1 (en) * | 2003-02-20 | 2004-09-02 | Tor Persson | Method for installing a self-floating deck structure onto a buoyant substructure |
| CN109790823A (en) * | 2016-05-13 | 2019-05-21 | 埃斯特科股份公司 | The auxiliary floating system of installation and/or transport for offshore structure and including the method for the system |
| WO2022118056A1 (en) * | 2020-12-01 | 2022-06-09 | Totalenergies Onetech | Floating installation having a reduced excursion around a desired position |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3031997A (en) * | 1957-04-30 | 1962-05-01 | William A Nesbitt | Floating platform |
| DE2403201A1 (en) * | 1973-01-23 | 1974-07-25 | Takenaka Komuten Co | AMUSEMENT BOAT FOR OBSERVATIONS IN THE SEA |
| FR2261170A1 (en) * | 1974-02-19 | 1975-09-12 | Shell Int Research | |
| DE2641040A1 (en) * | 1976-09-11 | 1978-03-16 | Marine Service Gmbh | FLOATING GAS LIQUIDATION PLANT |
| DE2654054A1 (en) * | 1976-11-29 | 1978-06-08 | Hermann Wienands | Marine platform for mineral extraction - has drilling tower stabilised by water circulating in tubular rings |
-
1984
- 1984-12-07 FR FR8418863A patent/FR2574367A1/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3031997A (en) * | 1957-04-30 | 1962-05-01 | William A Nesbitt | Floating platform |
| DE2403201A1 (en) * | 1973-01-23 | 1974-07-25 | Takenaka Komuten Co | AMUSEMENT BOAT FOR OBSERVATIONS IN THE SEA |
| FR2261170A1 (en) * | 1974-02-19 | 1975-09-12 | Shell Int Research | |
| DE2641040A1 (en) * | 1976-09-11 | 1978-03-16 | Marine Service Gmbh | FLOATING GAS LIQUIDATION PLANT |
| DE2654054A1 (en) * | 1976-11-29 | 1978-06-08 | Hermann Wienands | Marine platform for mineral extraction - has drilling tower stabilised by water circulating in tubular rings |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2613315A1 (en) * | 1987-04-02 | 1988-10-07 | Frelat Eric | Rotation, translation on the dynamics of a secured insubmergible volume |
| WO1997047515A1 (en) * | 1996-06-11 | 1997-12-18 | Jenan Kazim | Improved tethered marine stabilising system |
| US6241425B1 (en) | 1996-06-11 | 2001-06-05 | Jenan Kazim | Tethered marine stabilizing system |
| US5983822A (en) | 1998-09-03 | 1999-11-16 | Texaco Inc. | Polygon floating offshore structure |
| US6230645B1 (en) | 1998-09-03 | 2001-05-15 | Texaco Inc. | Floating offshore structure containing apertures |
| US6712560B1 (en) | 2000-12-07 | 2004-03-30 | Fmc Technologies, Inc. | Riser support for floating offshore structure |
| WO2004074086A1 (en) * | 2003-02-20 | 2004-09-02 | Tor Persson | Method for installing a self-floating deck structure onto a buoyant substructure |
| CN109790823A (en) * | 2016-05-13 | 2019-05-21 | 埃斯特科股份公司 | The auxiliary floating system of installation and/or transport for offshore structure and including the method for the system |
| WO2022118056A1 (en) * | 2020-12-01 | 2022-06-09 | Totalenergies Onetech | Floating installation having a reduced excursion around a desired position |
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